Richard Branson plans to stay on Necker Island during Hurricane Irma -- even though Irma is a Category 5 hurricane and the British Virgin Islands lies directly in the path of the storm. Of course taking a risk like that is exactly the sort of thing Sir Richard loves to do.

And in spite of the fact that Branson says that the facilities on Necker Island had been built to withstand hurricanes and severe weather, but that "almost nothing" can withstand a Category 5 hurricane.

So why is he staying?

For one thing, the experience. Branson, like most entrepreneurs, loves trying new things -- and like many ideas, sees the process as important as the outcome. "It may sound strange, but I consider hurricanes one of the wonders of the natural world," he wrote yesterday. "Two powerful hurricanes, Earl and Otto, hit the BVI in 2010 and caused extensive damage. I beheld nature at its most ferocious. The power of the sea breaking over the cliff tops, the eerie hush when you are in the eye of the hurricane and then the roar of the winds, the lightning and the rain."

Yep. He wants to see Hurricane Irma. He wants to experience Hurricane Irma.

Of course that also means he could die in Hurricane Irma.

Which once again begs the question: Why doesn't he do what would seem to be the smart thing, and leave?

I'm just guessing, but partly it's due to a feeling of community. Not everyone in the B.V.I. has the resources to leave. Branson does, but I bet he's staying due to a feeling of community and solidarity with the people who live in a place he now considers home.

But more to the point, Branson possesses a heaping helping of irrational optimism, a trait science shows is shared by many entrepreneurs, especially serial entrepreneurs.

To be successful, entrepreneurs must embrace belief, which means pushing aside all those self-doubts: Feeling you aren't smart enough, dedicated enough, adaptable enough, or simply that, in spite of your best intentions and best efforts, you won't succeed.

Other people often make it even harder to maintain that belief. Family and friends tend to shoot multiple holes in your ideas, not because they want to bring you down, but because they care about you and don't want to see you fail.

That's why people rarely say, "Hey, that's a great idea. You should go for it!" Most people aren't wired that way. Most people -- myself definitely included -- are a lot better at identifying and listing potential problems. (Or we like to play devil's advocate, because that makes us seem smart.)

That's why entrepreneurs need to be irrationally optimistic: Not because the odds are stacked against success, but because irrational optimism helps them succeed in ways capital, business plans, and marketing savvy can't.

Maybe Branson is taking irrational optimism too far. Maybe entrepreneurs take irrational optimism too far.

Then again, maybe you can't.

Think about sports, the ultimate zero-sum game. Only one individual or one team can win, but great athletes still go into every game believing they will win -- because if they don't believe they can win, they've already lost.

Is complete self-belief irrational? Sure. Is it also a requirement for high-level athletic success? Absolutely. Great athletes push aside doubt and disbelief.

So do great entrepreneurs.

If you listen to the naysayers you'll never start a business, never expand, never work and struggle and overcome--and never succeed. If you don't believe in yourself, however irrationally, you will not succeed.

Although no amount of self-belief is enough to ensure success, the smallest bit of doubt can ruin your chances.

In Bounce, Matthew Syed quotes Arsenal manager Arsene Wenger, one of the most successful football (soccer) coaches in the English Premier League, on how athletes must approach competition:

To perform to your maximum you have to teach yourself to believe with an intensity that goes way beyond logical justification. No top performer has lacked this capacity for irrational optimism; no sportsman has played to his potential without the ability to remove doubt from his mind.

The same is true for entrepreneurs -- and, really, for everyone. Be smart, be logical, be rational and calculating, and never stop trying to improve your skills. But most important, be irrationally optimistic.

Belief in yourself will take you to places no external forces ever can.

To me, that's why Sir Richard is staying on Necker Island. Staying means more to him than leaving. Experiences mean more to him than fear.

And there's one other thing: He's irrationally optimistic.

And that's likely why he's so successful.